Contact mechanism for electric watch



Oct. 4, 1960 P. E. BIEMILLER ETAL 2,954,653

CONTACT MECHANISM FOR ELECTRIC WATCH Filed Dec. 8, 1955 2 Sheets-Sheet 1 Fig. 2

INVENTOR Philip E. Biemiller James H. Reese Harry S. Dehuiler ATTORNEY 1960 P. E. BIEMILLER ETAL' 2,954,663

CONTACT MECHANISM FOR ELECTRIC WATCH Filed Dec. 8, 1955 2 Sheets-Sheet 2 INVENTOR Philip E. Bicmiller James H. Ruse Harry S. Och-Her ATTORNEY United States Patent O CONTACT MECHANISM FOR ELECTRIC WATCH Philip E. Biemiller, Landisville, James H. Reese, Manheim, and Harry S. Detwiler, Lancaster, Pa., assignors to Hamilton Watch Company, Lancaster, Pa., a corporation of Pennsylvania Filed Dec. 8, 1955, 'Ser. No. 551,791

18 Claims. (Cl. 58-28) This invention relates to a cont-act making and breaking system and apparatus for battery operated electric wrist witches, and more particularly a contact making and breaking system in which the contact pressure is maintained substantially constant from the initial contact to the point of breaking.

In the development of an electrically operated wrist watch the-problem of making a contact which is free from vibration and which will maintain a constant pressure during the making period to prevent erosion of the contacts and to produce a uniform flow of current during the contact interval made it necessary to provide contacts which were prestressed and to provide means for bringing the contacts into contact making position, and means for positively breaking the contacts at the end of a definite period of time. This period of time is in the nature of .005 second and the contacting area is extremely minute. Because of the smallness of the parts, the comparative small amount of electric current involved (3X10- amperes) and the necessity for maintaining tolerances to of an inch renders the problem entirely difierent from that of an ordinary electric contact.

In a watch of the permanent magnet, oscillating coil type the electric coil which is carried on the balance wheel is energized on the forward swing of the balance wheel at the moment the coil passes over the permanent magnets. This energization of the coil produces a magnetic flux within the coil which acts opposite to the permanent magnetic field and produces a thrust or kick against the coil which swings the balance wheel in one direction. The motion of the balance wheel is arrested and returned by the usual hairspring, at which time, the backward swing of the balance wheel, the coil is not energized during its passage through the permanent magnetic field.

It is the object of this invention to provide a prestressed contact which may be brought into engagement with an oscillating contact and which will at its very first engagement make the contact with a pressure which will be maintained during the entire period of contact and will break under the action of a force which will minimize any arcing.

It is a further object of the present invention to provide a contact making arm for engaging an oscillating contact which is adjustably mounted in a pin so that it has a tendency to move in the direction of contact making, and to provide a spring arm adapted to hold the contact making arm in stressed predetermined position and to release that holding force so that the contact arm may engage the oscillating contact with a predetermined force and maintain that force against the oscillating con- 2,954,663 Patented Oct. 4, 1960 tact during the contact interval, the contact being broken by a force supplied against the contact bearing arm returning said contact arm to its original position.

It is a further object of the present invention to provide a spring arm carrying a contact mounted for adjustment both longitudinally and horizontally and a second spring arm engaging and controlling the action of said contact carrying spring arm, said second spring arm being mounted for adjustment both longitudinally and horizontally.

It is a further object of the present invention to provide a contact bearing spring arm adjustably mounted and a second spring arm adjustably mounted, said second spring arm controlling the action of said contact carrying spring arm during the making and breaking operation and providing means carried on the oscillating balance wheel for engaging the second spring arm.

It is a further object of the present invention to provide a contact making system which will be energized during the oscillation of the balance wheel in one direction (forward) and which will be swung out of contact making position during the movement of the balance wheel in the opposite direction (backward).

It is a still further object of the present invention to provide spring arms which are of extended length so that on the back swing of the balance wheel the spring arms oifer a minimum amount of resistance to the movement of the balance wheel to thus preserve as much of the energy as possible.

It is a still further object of the present invention to provide spring contact making arms and spring controlled arms of rectangular cross section to provide relative stability against shock in one direction while permitting relative flexibility in the other direction.

It is a still further object of the present invention to provide for horizontal movement between the contacts during the contact making period.

The invention is shown in the accompanying drawings in which:

Figure 1 is a top plan view showing the contact making mechanism and the balance wheel.

Figure 2 is a side elevation of the same.

Figure 3 is a top plan greatly enlarged showing the different positions of the contact making arm during the contact interval.

Figure 4 is a further enlargement of a detail shown in Figure 3.

Figure 5 is a detail of the mechainsm shown in Figure 3 and illustrating the adjustability of the controlling spring arm.

Figure 6 is a cross sectional view of one of the spring arms taken on line 6-6 of Figure 4.

Referring particularly to Figures 1 and 2, the balance wheel of a battery operated electric watch is shown with a rim 12, a cross bar 14, a coil 16, and a balance staff 18. The balance wheel is caused to oscillate through the action of the coil 16 passing through a permanent magnetic field created by a pair of small cylindrical permanent magnets 15, the coil being energized by contact with a battery 20 grounded at 22 to the mechanism of the watch and through a balance cock, stud, hairspring and collet (not shown) to the staff 18, the cross bar 14, to the rim 12 which in turn is connected to the coil at 24. The other end of the coil 26 is wrapped around and soldered to a bracket 28 to which is attached an electric contact strip 30 by a screw 32.

. 3 The contact strip is secured to the bracket 28 by the screw 32 passing through a slot 34 in the contact strip which allows the contact strip to be initially positioned radially on the balance Wheel to provide vfor any small difierences in the size of the coils or in the distance that the coil is mounted in the balance wheel from the balance staff. The exact radial position of the contact strip 30 is extremely important so that initial adjustment must be provided. A roller 36 is carried on the balance staff above the cross bar 14 and serves to support the contact strip 30. Insulation 38 serves-to prevent grounding of of the contact strip against either the roller or the staff. The contact strip curves substantially in a semicircle around the balance stall and terminates in a vertical finger 46 having a comparatively broad base 42 and a narrower end portion 44.

The roller 36 instead of being round is extended in substantially teardrop shape, the extension 46 providing a support tor a pin 48. Referring to Figure 4 and considering the movement of the balance wheel in a counterclockwise direction to be forward and the movement of the balance wheel in a clockwise direction to be backward, the pin 48 is formed of substantially wedge shaped cross section and mounted rigidly in the extension 46 of the roller 36 in an exact relationship to the upright end 40 of the contact strip which is cemented or otherwise secured to the roller 36. The pin 48 is formed of sapphire and has a flat surface 49 in a forward direction and slightly ofi of a radial line of the balance wheel. The pin is positioned so that its backward tace 50 will permit a quick disengagement with the controlling spring arm.

A plate 54 secured to the pillar plate or other supporting member (not shown) of the watch carries a post 56 and a second post 58. Each of these posts has respectively mounted thereon a collet 60 and 62 and are insulated from the plate 54 by an insulating sleeve 64. The collets 60 and 62 are friction held to their respective .posts and may be rotated about the posts to provide angular adjustment of the spring arms. Slots 65 and 66 formed in the respective collets 60 and 62 are angularly positioned with respect to each other by rotating either or both of the collets on their respective posts.

A controlling spring arm 68 is mounted in the slot 65 of the collet 60. A second spring arm 70 is mounted in the slot 66 of the collet 62. The spring arm 70 is mounted at a slightly higher level above the plate 54 than the spring arm 68 and is prevented from swinging over and beyond the arm 68 by a tab 69 which projects upward from the spring arm 68 into the path of swinging movement of the arm 76. The second spring arm carries at its end a substantially conical shaped electric contact 72 adapted to engage the vertically positioned end 40 (at 44) of the contact strip 30.

The first spring arm 68 mounted in the collet 60 serves as a controlling and limiting member, through engagement of the spring arm 78 with the vertical tab 69, for the second electric contact carrying spring arm and will hereinafiter be referred to .as the controlling spring arm, while the second arm 70 carries the electric contact 72 and will hereinafter be referred to as the contact carrying spring arm. The controlling spring arm 68 is longitudinally adjustable in the slot 65, which longitudinal adjustment controls the position at which its end 74 contacts the forward face of the pin 48 as shown in Figure 5, being adjustable between the limits as shown in the solid lines to that shown in the dotted lines. This adjustment can be used to partially control duration of contact. The controlling spring arm 68 is still further adjusted in its angular relation to the contact carrying spring arm 70 by rotating the collet 60 about the post 56. The latter of these adjustments can be made during the operation of the Watch. The contact carrying spring arm 70 is adjustable in a like manner, that is longitudinally in the slot 66 and .angularly by moving the collet 4 62 about its post 58. This too partially controls the duration of contact period. Furthermore, the angular adjustment of the collet 62 on the shaft 58 provides the stress in the contact spring arm 70 and determines the force between the contact 72 and the upright end 40 of the contact strip 30.

Each of the spring arms is normally positioned angularly so that they would cross one .above the other. This crossing, however, is prevented by the engagement of the spring arm 74) with the vertical tab 69 so that both spring arms are maintained in a stressed position, each directing a force against the other.

The angular relation between the controlling spring arm and the contact spring arm is extremely important and is determined by the angle of the slots 65 and 66. Referring particularly to Figure 3, the members as shown in solid lines are in a balanced position with the stress of the controlling arm acting against the stress of the contact carrying arm to hold them in normal position.

The spring arms 68 and 70 are rectangular in cross section, as shown in Figure 6, and comparatively long. The cross sectional area permits :a maximum of flexibility in a plane parallel to the balance wheel and the path of movement of the contact, while in the other direction there is an inherent rigidity against bending which serves to maintain the spring arms in position against the ordinary shocks which occur in the wearing of a wrist watch. The comparative length of the spring arms permits the balance wheel on its oscillation in which there is no contact made to move the spring arms from the path of the contact with a minimum expenditure of energy.

In the running of the watch, current flowing from the battery 20 energizes the coil only at the moment that it is in the magnetic field and produces a magnetic thrust against the coil which is transmitted to the balance wheel which with the reaction of the hairspring produces oscillating motion. The oscillation of the balance wheel moves the roller and its jewel pin and vertical contact member 40. The oscillating movement of the pin and the contact member 40 (Figures 3 and 4) causes the forward face of the pin to engage the end 74 of the controlling spring arm 68 and move it in a clockwise direction. Swinging movement of the controlling arm 68 is followed by a like movement and in the same direction of the contact carrying spring arm 70 by reason of the stress within the arm. Further movement of the pin 48 in a counterclockwise direction moves the controlling arm 68 in a clockwise direction, causing the end 74 to move across the forward face of the pin 48 and bringing the contact 72 into engagement with the upright end 40, at 44, of the contact strip 30. Immediately upon engagement of the contact point 72 with the face 76 of the upright end 40, the movement of the contact carrying spring arm is restrained and the stress within that arm is partially absorbed at the contact making point. It will thus be seen that the contact 72 is urged against the face 76 with a predetermined force so that there is no possibility of chatter between the contact point 72 and the face 76, that the arcing between the two is minimized by this steady force, and that the contact 72 from the beginning to the end of the contact making period is held against the face 76 with substantially the same force. Further movement of the roller and its accompanying pin 48 moves the end 74 of the controlling spring arm 68 so that its end passes the rounded nose 78 of the pin 48 and drops sharply away from the pin because of the cut away face 50. This sharp dropping snaps the upright tab 69 of the controlling spring arm 68 against the contact carrying spring arm 70 causing a sharp break between the face 76 and the contact 72 and snapping the spring arms 70 and 68 back to normal position.

During the contact making operation, that is from the time the contact 72 contacts the face 76 until it is broken by movement of the controlling spring arm 68, there is 5. a relative motion in a radial direction across the face 76 of the upright contact 44 by the contact 72. This motion, though slight, is shown in Figure 4, the diiference between the dotted line position of 72 and the solid line position of 72. This motion is caused by oscillating movement of the balance wheel and its carried contact 40. Because the length of the contact carried spring arm 70 is constant, the movement of the contact 40 with the staff 18 causes a slight movement in a radial direction across the face 76 of the upright 44 and preserves a clean contact making surface at all times. It will thus be seen that due to the force caused by the stress in the arm 70, a substantially constant contact against the face 76 with a slight wiping action is made during the contact making period.

Referring particularly to Figure 5, the controlling spring arm 68 is shown engaging the pin at a point 80. This provides for a short duration of contact, that is the length of time it takes for the end 74 of the controlling spring arm to move from the point 80 to the rounded nose 78 of the forward face of the pin 48. By adjusting the controlling spring arm 68 in the slot 65 this may be varied and the point of contact with the forward face of the pin 48 may be changed to a point 82 which will materially affect the period of contact making due to the increased distance the end 74 of the controlling spring arm 68 has to travel before reaching the nose 78. This adjustment will control the duration of contact making and materially aifect the timekeeping of the watch.

During the backward movement of the balance wheel the spring arms being located in the path of that movement are engaged and swung from the path of movement. This engagement takes place by the end 74 of the controlling spring arm 68 engaging the face 50 of the pin 48 and moving both of the spring arms in a counterclockwise direction until the end 74 slips past the rounded nose 78. The comparative extended length of the spring arms make it possible for the balance wheel to push the spring arms out of position on its backward oscillation with a minimum expenditure of energy.

What is claimed is:

1. In an electric watch operated by a battery, an oscillating balance wheel, an oscillating electrical contact member, a second prestressed electrical spring contact member adapted to engage said oscillating contact member during a portion of its oscillating movement, said second contact member engaging said oscillating contact member with a predetermined force, means carried by said balance Wheel for moving said second contact member away from the equilibrium position of said oscillating electrical contact member whereby said predetermined force is maintained substantially constant during the contact making interval.

2. An electric watch operated by a battery as described in claim 1, including means to vary the amount of prestress in said second electrical spring contact member.

3. In an electric watch operated from a battery, a pcriodically energized oscillating coil, a first electrical contact member mounted for rotation with said coil, and a prestressed electrical spring contact member adapted to engage said contact member mounted for rotation with said coil with a force which is held substantially constant during the contacting period to connect said coil to said battery.

4. An electric watch operated from a battery as described in claim 3 including means to vary the amount of prestress in said second electrical spring contact member.

5. In an electric watch, an oscillating balance wheel supporting a periodically energized coil and carrying a contact member, a pair ofspring arms held in stressed position by engagement one with the other, an electric contact carried by one of said arms, means carried by said balance wheel for moving the other of said arms away from the equilibrium position of the contact carrying arm, whereby said arm carried contact is moved into engagement with said balance wheel carried contact member, under a force which is held substantially constant during the contacting interval.

6. In an electric watch, an oscillating balance wheel supporting a periodically energized coil and carrying a contact member, a pair of spring arms held in stressed position by engagement one with the other, an electric contact carried by one of said arms, means carried by said balance wheel for engaging and moving the other of said spring arms away from the equilibrium position of the contact carrying arm during the oscillating move ment, whereby said arm carried contact is moved into engagement with said balance Wheel carried contact member under a force which is held substantially constant during the contacting interval, continued movement of said balance wheel disengaging said means with said spring arm to permit a return to equilibrium position of said spring arms.

7. In an electric watch, an oscillating balance wheel supporting a periodically energized coil and carrying a contact member, a pair of spring arms held in stressed position by engagement one with the other, an electric contact carried by one of said arms, means carried by said balance wheel for engaging the other of said spring arms for a predetermined angle during the oscillation of the balance wheel, releasing said contact carrying spring arm and permitting engagement between said spring arm carried contact and said balance wheel carried contact member, whereby said arm carried contact is moved into engagement with said balance Wheel carried contact member under a force Which is held substantially constant during the contacting interval, continued movement of said balance wheel disengaging said means with said spring arm to permit a return to equilibrium position of said spring arms, said return breaking the engagement between said spring arm carried contact and said balance wheel carried contact, and means for adjusting said spring arms to determine the duration of said contact interval.

8. An electric watch having a pair of spring arms according to claim 7, wherein the means for adjusting the spring arms comprises a supporting pin, a collet mounted on said supporting pin and formed with a slot, one of said spring arms being slidably mounted in said slot, the collet being mounted for rotation on said pin so that one of said spring arms can be adjusted both longitudinally and angularly with relation to the balance wheel and its companion spring arm.

9. An electric watch having a pair of spring arms according to claim 7 in which the means for adjusting the spring arms comprises a plate, a pair of pins mounted on said plate, a pair of collets formed with a slot rotatably mounted on said pins, the spring arms being respectively carried in the slots of the collets to provide both angular and longitudinal adjustment of both of the spring arms relative to each other and to the balance wheel.

10. In an electric watch having an oscillating balance wheel supporting a periodically energized coil and carrying a contact member, a pair of spring arms positioned so as to be held in a stressed equilibrium position by engagement one with the other, means for adjusting the relative position to vary the force between. them, an electric contact carried by one of said arms, means carried by said balance wheel for moving the other of said arms away from the equilibrium position of the contact carrying arm, whereby said arm carried contact is moved into engagement with said balance wheel carried contact member under a force which is held substantially constant during the contacting interval.

11. In an electric watch having an oscillating balance wheel supporting a periodically energized coil and carrying a contact member, a pair of spring arms positioned so .as to be held in a stressed equilibrium position'by engagement one with the other, means for adjusting the relative position to vary the force between them, an electric contact carried by one of said arms, means carried by said balance wheel for moving the other of said arms away from the equilibrium position of the contact carrying arm, whereby said arm carried contact is moved into engagement with the balance wheel contact carried member under a force which is held substantially constant during the contacting interval, the said contact moving longitudinally across the face of the balance wheel carried contact member during said contacting interval.

12. In an electric Watch having an oscillating balance wheel supporting a periodically energized coil and carrying a contact member, a pair or" spring arms, an electric contact carried by one of said arms, means on said balance wheel for engaging the non-contact carrying arm to periodically bring said spring arm contact into engagement with said balance wheel contact member, said spring arms being of cross sectional dimensions, greater in one direction than in the other to give a comparative rigidity in one direction and a comparative flexibility in the other direction and being mounted so as to engage and stress one another.

13. In an electric watch having an oscillating balance wheel supporting a coil and carrying a contact member connected to said coil, a pair of spring arms, an electric contact carried by one of said spring arms and adapted to be brought into engagement with said balance wheel carried contact member to periodically electrically energize said coil, means carried by said balance wheel engaging the non-contact carrying spring arm and moving said contacts into and out of contact making position, said spring arms having cross sectional dimensions, greater in one direction than in the other to provide relative rigidity against movement in a vertical direction and relative flexibility for movement in a horizontal direction.

14. In an electric watch operated by a battery, a balance staff, a balance wheel supported by said stall and oscillating therewith, a coil carried by said balance wheel, an electric contact member adjustably connected to said coil, said contact member being substantially in the plane of the balance wheel, the extreme end of said contact member being bent at right angles to form a vertical contact making end, a roller carried by said balance staif, said roller together with said coil supporting said contact member, an upright pin carried by said roller formed of substantially wedge shaped cross section and having its forward face positioned substantially radial with respect to said balance wheel, a controlling spring arm adjustably mounted in the path of movement of said pin, an adjustable electric contact carrying spring arm adapted to be positioned in the path of movement of said contact making end of said contact member, said spring arms being anguiarly positioned normally to cross each other, a vertical tab carried by the controlling spring arm and extending into the path of movement of'the contact carrying spring arm to restrict such crossing and hold said spring arms in contact and under the stress of their inherent resiliency, each exerting a force against the other, the oscillating movement of the balance wheel bringing the forward face of the pin into engagement with the end of the controlling spring arm to move said spring arm away from engagement with said contact carrying spring arm permitting the engagement of said spring arm contact with said contact making end with the force due to the inherent resiliency of the contact carrying spring arm, subsequent movement of said oscillating wheel breaking the engagement of the end of said controlling arm with the pin, said controlling arm snapping back under its inherent resiliency so that said tab snaps into engagement with said contact carrying spring arm breaking engagement between said contact and said contact making end, movement of the balance wheel in the opposite direction bringing the end of the controlling spring arm into engagement with the pin and swinging said contact carrying spring arm out of the path of movement ofthe contact making end.

15. In an electric wrist watch, -a battery, a permanent magnet, a balance wheel and hairspring assembly mounted on a balance staff, a coil carried by and oscillating with said balance Wheel, said coil passing through the magnetic field of said permanent magnet during the oscillatory movement, an electric contact member connected to said coil and carried by and oscillating with said balance wheel, a roller mounted on said balance staff and oscillating with said balance wheel, a pin of wedge shaped cross section carried by said roller and positioned so that its forward face is substantially radial with respect to said balance wheel, a controlling spring arm, an electric contact carrying spring arm, means for mounting said arms so as to be angularly adjustable with relation to each other and adjustable with relation to said roller carried pin and said balance wheel carried contact member to vary the contact making interval and the spring arm contacting forces, said spring arms being of cross sectional dimensions, greater in one direction than in the other to have comparative rigidity in one plane to maintain said spring arms in the path of movement of the balance wheel carried pin and contact member, and comparative flexibility in a plane normal to said first mentioned plane to permit contact with said balance Wheel carried pin and contact member without affecting the timekeeping motion of said balance wheel, said spring arms by reason of their relative angular position being held in a stressed position and in contact with each other to provide a constant force against said balance Wheel carried contact member during the contact making in terval.

16. in an isochronal device operated by a battery, a coil mounted for oscillation through a magnetic field, means for periodically connecting said coil to said battery comprising an oscillating balance wheel, a first electrical contact mounted for rotation with said coil, and a second prestressed electrical spring contact member mounted in a position to engage said first electrical contact with a predetermined force, means carried by said balance wheel for moving said second contact member away from the equilibrium position of said oscillating electrical contact member whereby said predetermined force is maintained substantially constant during the contact making interval.

17. In an isochronal device operated by a battery, coil mounted for oscillation through a magnetic field, means for periodically connecting said coil to said battery comprising a first electrical contact mounted for rotation with said coil at a point eccentric of the axis of oscillation of said coil, and a pair of spring arms held in a stressed equilibrium condition by engagement with one another, an electrical contact carried by one of said arms, means mounted for oscillation with said coil for moving the other of said arms away from the equilibrium position so that said arm carried contact is moved into ongagement with said first electrical contact under a force which is substantially constant throughout the contact period.

18. In an isochronal device, an oscillating balance wheel supporting a periodically energized coil and carrying an electric contact member, a pair of spring arms held in stressed position by engagement with one another, an electric contact carried by one of said arms, means car ried by said balance wheel for engaging the other of said spring arms for a predetermined angle during the oscillation of the balance wheel, releasing said contact carrying spring arm and permitting engagement between said spring arm carried contact and said balance wheel carried contact member, whereby said arm carried contact is moved into engagement with said balance Whecl carried contact member under a force which is held substantially constant during the contacting interval, continued movement of said balance wheel disengaging said means with said spring arm to permit a return to equilibrium position of said spring arms, said return breaking the engagement between said spring arm carried contact and said balance wheel carried contact, and means for adjusting 5 said spring arms to determine the duration of said contact interval.

UNITED STATES PATENTS Thornton-Norris Dec. 12, 1950 Black July 7, 1953 Van Horn et a1 Sept. 17, 1957 Beyner Sept. 30, 1958 FOREIGN PATENTS Switzerland Sept. 1, 1948 

